Fig. 1.

Schematics showing the derivation of mammalian haploid embryonic stem cells. a, b Androgenetic haploid embryos have been generated by removing the maternal pronucleus from the zygote (a) or injecting a sperm head into an enucleated oocyte (b). Then, the mouse AG-haESCs are obtained from the derived AG-ESCs using FACS. c Procedure for producing rat AG-haESCs. Allodiploid ESCs are obtained through the fusion of mouse and rat AG-haESCs. d, e Parthenogenetic haploid embryos are generated from MII oocytes activated by 10 mM SrCl₂ in calcium-free CZB medium without CB (d) or through the removal of the male pronucleus from the zygote (e). a–e Blastocysts or ES cells shown in light colors are haploid cells and darker colored cells are diploid cells